• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.3
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• pp.282-292
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• 2015

Seeds of colored rice generally have high anthocyanin and flavonoid content but some cultivars have low seed germination rate. This defect poses unstable seedling establishment in nursery bed. The seed gravity variations of 10 colored rice varieties and its effect on germination, seed soaking duration and their optimum seeding rates for seedling raising in machine transplanting were investigated in the experiment. Based on seed gravity distribution of the 7 black- and 3 red-colored rice varieties at three levels of seed gravity (1.0<, 1.0~1.06, 1.06>), the black colored seeds such as Josaengheugchal and Sinmyungheugchal had high amount of specific gravity of below 1.0 ranging from 86~ 96%, while they had only 3~13% of seeds in specific gravity above 1.06. Sintoheugmi, Heugjinju, Heugnam, Heugkwang had various mass of seeds, showing 29~44% for specific gravity of below 1.0, 24~39% for 1.0~1.06 and 25~45% for above 1.06. On the other hand, the red colored rice such as Hongjinju, Jeogjinju and Geonkanghongmi had high percentage of specific gravity of above 1.06 with 84~86% while they had only 9~12% of specific gravity below 1.0 similar to Ilmibyeo of noncolored rice. The black colored seed generally showed low germination percentage, slow germination speed and long mean germination time, and low water absorption rate as compared with seed of the red colored rice which was similar to those of Ilmibyeo used as a control cultivar. The black colored seeds took 2~4 days longer seed soaking duration than the red colored rice before germination. This was related to high seed amount of specific gravity below 1.0 in black colored rices. The high amount of seed gravity above 1.06 in the colored rice seeds was positively correlated with percentage of germination, germination speed and mean germination time, ripened grain ratio and water absorption. Seed gravity distribution effect were less pronounced between back- and red- colored seeds in seedling emergence. The black colored rice has slightly lower normal seedling emergence rate than the red colored rice and Ilmibyeo in the seedbed soil due to high percentage of ungerminated seed. Normal seedling emergence rate of the black colored rice in the seedbed was 75.2~82.2% for 10-day old seedling and 85.3~ 90.9% for 30-day old seedling which was lower by 4.5~ 8.0% and 0~3.3%, respectively, than the red colored rice. Based on the normal seedling number per tray of Ilmibyeo for seeding rate of 10-day and 30-day old seedlings, the recommended seeding rate of black colored rice is 200~ 220g seeds for the 10-day old seedling and 110~130g for the 30-day old seedling in transplanting rice while the seeding rate of the red colored rice was 220g seeds for the 10-day old seedling and 130g for the 30-day old seedling.

• Transactions of Materials Processing
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• v.19 no.6
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• pp.357-362
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• 2010

Dry sliding wear behavior of pure Fe and Cu which have BCC and FCC crystal structure, respectively, was investigated. The wear characteristics of the pure metals with different crystal structure were compared. Dry sliding wear tests were carried out using a pin-on-disk wear tester at various loads under the constant sliding speed condition of 0.15 m/s against a silica ball at room temperature. Sliding distance was fixed as 600 m for all wear tests. Wear rate of a specimen was calculated by dividing the weight loss of the specimen after the test by the specific gravity and sliding distance. Worn surfaces and wear debris were analyzed by SEM. The wear of both pure Fe and Cu proceeded with surface deformation, resulting in similar wear rates despite of their structure difference under the current test conditions. Wear rates of both metals were low if the surface deformation due to wear forms thick surface-deformation layer that is strain hardened beneath the wearing surface. The pure Cu specimens showed a lot of oxides on the worn surface when tested at low loads less than 5 N, which resulted in very low wear rate.

• Journal of Korea Technology Innovation Society
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• v.8 no.1
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• pp.135-153
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• 2005

With an explosive growth of internet and a change of consumer's demand, Post PC is emerging as a substitute for the existing desktop computer and laptop computer. Post PC is a new computer which is portable with wireless networking, cheaper than the existing PCs and specialized in the specific function that consumers want. Furthermore, the shape and the ability of Post PC are dependent on its specific function. The rudimentary Post PCs such as PDA, web-pad and smart-phone are already usable. And in the future, owing to the progress of technologies, the heterogeneity of relate companies and the low entry barrier, various Post PCs will be developed. In this paper, we analyze consumers' willingness-to-pay for Post PC with the attributes such as the portability, the speed of CPU, the data input method (using key board, or notepad etc), the size of monitor and price. To estimating consumers' willingness-to-pay for the attributes of Post PC, we apply a contingent ranking method, which makes the respondents rank hypothetical Post the portability, the speed of CPU, the data input method (using key board, or notepad etc),the size of monitor and price. To estimating consumers' willingness-to-pay for the attributes of Post PC, we apply a contingent ranking method, which makes the respondents rank hypothetical Post PC alternatives featuring various combinations of attributes, to a survey data collected in Korea. Using the estimated willingness-to-pay, we predict the shape and the ability of future's Post PC and draw policy implications for the national and company level R&D strategies.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.306-309
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• 2007

Japanese Ocean Flux Data Sets with Use of Remote Sensing Observations (J-OFURO) includes global ocean surface heat flux data derived from satellite data and are used in many studies related to air-sea interaction. Recently latent heat flux data version 2 was constructed in J-OFURO. In version 2 many points are improved compared with version 1. A bulk algorithm used for estimation of latent heat flux is changed from Kondo (1975) to COASRE 3.0(Fairall et al., 2005). In version 1 we used NCEP reanalysis data (Reynolds and Smith, 1994) as SST data. However, the temporal resolution of the data is weekly and considerably low. Recently there are many kinds of global SST data because we can obtain SST data using a microwave radiometer sensor such as TRMM/MI and Aqua/AMSR-E. Therefore, we compared many SST products and determined to use Merged satellite and in situ data Global Daily (MGD) SST provided by Japan Meteorological Agency. Since we use wind speed and specific humidity data derived from one DMSP/SSMI sensor in J-OFURO, we obtain two data at most one day. Therefore, there may be large sampling errors for the daily-mean value. In order to escape this problem, multi-satellite data are used in version 2. As a result we could improve temporal resolution from 3-days mean value in version 1 to daily-mean value in version 2. Also we used an Optimum Interpolation method to estimate wind speed and specific humidity data instead of a simple mean method. Finally the data period is extended to 1989-2004. In this presentation we will introduce latent heat flux data version 2 in J-OFURO and comparison results with other surface latent heat flux data such as GSSTF2 and HOAPS etc. Moreover, we will present validation results by using buoy data.

• Journal of the Korean Society of Industry Convergence
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• v.17 no.4
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• pp.234-244
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• 2014

Recently it has been focused that the automobile engine has developed in a strong upward tendency for the use of the high viscosity and poorer quality fuels in achieving the high performance, fuel economy, and emission reduction. Therefore it is not easy to solve the problems between low specific fuel consumption and exhaust emission control at motor cars. In this study, it is designed and used the engine test bed which is installed with turbocharger and intercooler. In addition to equipped using CRDI by controlling injection timing with mapping modulator, it has been tested and analyzed the engine performance, combustion characteristics, and exhaust emission as operating parameters, and they were engine speeds(rpm), injection timing(bTDC), and engine load(%). From the result of an experimental analysis, peak cylinder pressure and the rate of pressure rise were increased, and the location of it was closer toward top dead center according to the increasing of engine speed and load, and with advancing injection timing. The combustion characteristics are effected by fuel injection timing due to be enhanced the mass burned fraction. Using the engine dynamometer for analyzing the engine performance, the engine torque and power have been enhanced according to advancing the fuel injection timing. In analyzing of exhaust emission, there has been a trade-off between PM and NOx with increasing of engine speed and load, and with advanced injection timing. The experimental data are shown that the formation of NOx has increased and PM, vice versa.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.9B
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• pp.939-946
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• 2009

In this paper, we propose a new network ASIP(Application Specific Instruction-set Processor) which was designed for simulation models by a machine descriptions language LISA(Language for Instruction Set Architecture). This network ASIP is aimed for an exclusive engine undertaking packet processing in a router. To achieve the purpose, we added a new necessary instruction set for processing a general ASIP based on MIPS(Microprocessor without Interlock Pipeline Stages) architecture in high speed. The new instructions can be divided into two groups: a classification instruction group and a modification instruction group, and each group is to be processed by its own functional unit in an execution stage. The functional unit was optimized for area and speed through Verilog HDL, and the result after synthesis was compared with the area and operation delay time. Moreownr, it was allocated to the Macro function ana low-level standardized programming language C using CKF(Compiler Known Function). Consequently, we verified performance improvement achieved by analysis and comparison of execution cycles of application programs.

• Journal of the Korea Society of Computer and Information
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• v.22 no.2
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• pp.1-7
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• 2017

Recently, NAND flash memory, which is used as a storage medium, is replacing HDD (Hard Disk Drive) at a high speed due to various advantages such as fast access speed, low power, and easy portability. In order to apply NAND flash memory to a computer system, a Flash Translation Layer (FTL) is indispensably required. FTL provides a number of features such as address mapping, garbage collection, wear leveling, and hot data identification. In particular, hot data identification is an algorithm that identifies specific pages where data updates frequently occur. Hot data identification helps to improve overall performance by identifying and managing hot data separately. MHF (Multi hash framework) technique, known as hot data identification technique, records the number of write operations in memory. The recorded value is evaluated and judged as hot data. However, the method of counting the number of times in a write request is not enough to judge a page as a hot data page. In this paper, we propose hot data identification which considers not only the number of write requests but also the persistence of write requests.

• International Journal of Aeronautical and Space Sciences
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• v.12 no.2
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• pp.190-199
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• 2011

Unsteady flow simulations of complete helicopter configurations were conducted, and the flow fields and the aerodynamic interferences between the main rotor, fuselage, and tail rotor were investigated. For these simulations, a three-dimensional flow solver based on unstructured meshes was used, coupled with an overset mesh technique to handle relative motion among those components. To validate the flow solver, calculations were made for a UH-60A complete helicopter configuration at high-speed and low-speed forward flight conditions, and the unsteady airloads on the main rotor blade were compared to available flight test data and other calculated results. The results showed that the fuselage changed the rotor inflow distribution in the main rotor blade airloads. Such unsteady vibratory airloads were produced on the fuselage, which were nearly in-phase with the blade passage over the fuselage. The flow solver was then applied to the simulation of a generic complete helicopter configuration at various flight conditions, and the results were compared with those of the CAMRAD-II comprehensive analysis code. It was found that the main rotor blades strongly interact with a pair of disk-vortices at the outer edge of the rotor disk plane, which leads to high pulse airloads on the blade, and these airloads behave differently depending on the specific flight condition.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.561-562
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• 2008

The numerical analysis of sound radiation by vibrating structure is a well known and mature technology used in many industries. Accurate methods based on the boundary or finite element method have been successfully developed over the last two decades and are now available in standard CAE tools. These methods are however known to require significant computational resources which, furthermore, very quickly increase with the frequency of interest. The low speed of most current methods is a main obstacle for a systematic use of acoustic CAE in industrial design processes. In this paper we are going to present a set of innovative techniques that significantly speed-up the calculation of acoustic radiation indicators (acoustic pressure, velocity, intensity and power; contribution vectors). The modeling is based on the well known combination of finite elements and infinite elements but also combines the following ingredients to obtain a very high performance: o a multi-frontal massively parallel sparse direct solver; o a multi-frequency solver based on the Krylov method; o the use of pellicular acoustic modes as a vector basis for representing acoustic excitations; o the numerical evaluation of Green functions related to the specific geometry of the problem under investigation. All these ingredients are embedded in the ACTRAN/AR CAE tool which provides unprecedented performance for acoustic radiation analysis. The method will be demonstrated on several applications taken from various industries.

• International Journal of Aerospace System Engineering
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• v.3 no.1
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• pp.25-29
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• 2016

This paper highlights the performance of an impulse turbine which is a part of turbopump in a liquid rocket first stage engine. The turbopump, currently under development at Korea Aerospace Research Institute, has an impulse type turbine with 12 nozzles and a single rotor. The impulse turbine can archive high specific power with the low gas flow rates. The supersonic impulse turbine with a single rotor can make a simple structure. High-pressure gases are converted into the dynamic energy with flows through the 12 nozzles and drive the rotor to make the power for the pumps. The turbine test was performed in the high-pressured turbine test facility with air gas instead of burned gas. A hydraulic dynamometer was used to absorb the power from the turbine and control the rotational speed and torque. The test points were at several pressure ratios with 7 different rotational speeds. Results showed the efficiency was highest at the design pressure ratio. The efficiency was insensitive to the pressure ratio variation than the rotational speed. It was a typical characteristic in an impulse turbine.